In general, metered-dose inhalers (MDIs) are devices for dispensing medicaments, e.g. in aerosol form, to the lungs. Broadly speaking dispensers such as MDIs are comprised of two components: a container and a delivery device. The container holds the medication, e.g. dissolved or suspended in a propellant under high pressure to maintain a liquid phase. Additionally the container often comprises an internal metering valve, which is designed to release a precisely measured, reproducible dose of medicament when the valve is actuated. The delivery device typically includes an actuator and a mouthpiece. The actuator, which can be triggered by the user, for example by inhalation or manual operation, typically interacts with the metering valve of the container to induce release of a dose. The mouthpiece serves to direct the medication towards the user.
We have previously described a number of dispensers, see for example U.S. Pat. No. 7,721,731. We have also disclosed dosage counters for use with such dispensers, see for example WO 2010/103315. Further examples of dose counters and dispensers may be found in WO2005/060535, GB2372542 and US2011/259324.
It has been found that, during use of the dispenser and counter, manufacturing tolerances may in some instances affect the performance. As such, we have appreciated the need for an improved dispenser and an improved counter.